While recovering a downed US Government space satellite
("Operation Royce Explorer") from the ocean floor agent Sam Casey
was exposed to a large dose of radiation when the satellite
exploded during the salvage operation. The heavy release of
radiation disrupted Sam's DNA and unexpectedly turned him
invisible.

The watch was actually a miniaturized version of the Life Support
System that saved Sam's life after the accident. As long as the
three gold contacts at the base of the watch touched Sam's skin,
he stayed visible. When contact was broken, he vanished.

Sam Casey

Sam could stay invisible for 15 minutes a day without upsetting
his DNA; any longer and he would disintegrate (die).

A computerized countdown on the watch let Sam know how much time
he had left on his invisibility sessions. The countdown began when
Sam pressed on the watch's stem.

Sam and Abby reported to Leonard Driscoll, the director of
INTERSECT (International Security Technics, a government think
tank).